UKAS accredited Mass Calibration Service

Northern Ireland Trading Standards operate a Mass Calibration Service.

We are a United Kingdom Accreditation Service United Kingdom Accreditation Service (UKAS) accredited calibration laboratory (No. 0338) for the calibration of mass.  UKAS Calibration 0338 accreditation mark

Our ISO/IEC 17025 accreditation provides traceability to the SI system of units.

You can find more information in our full UKAS Schedule.

Type Class Material Weight Description

Precision Weights

OIML Class F1

Stainless Steel

1 mg to 25 kg

These classes of weights are typically used in precision engineering and pharmaceutical applications.

Test Weights

OIML Class F2

Stainless Steel, plated brass

1 mg to 25 kg

These class of weights are typically used by scale firms and businesses as the reference weights for checking the accuracy of weighing scales and platform scales used for industrial applications.

Test Weights

OIML Class M1

Brass, cast Iron, Aluminium.

1 mg to 25 kg

These class of weights are typically used by scale firms and businesses as the reference weights for checking the accuracy of weighing scales and platform scales used for industrial applications.

25g - 5kg Mass Comparator Calibration takes place in our laboratory where the environmental conditions are strictly controlled. Each item submitted for calibration is placed in the laboratory 24 hours prior to testing in order to acclimatise to these conditions. Once calibrated each item is returned with a fully traceable UKAS calibration certificate acceptable for most quality systems.


E2 standard weights The value of your weights will be determined by comparison through substitution weighing, with weights that can provide traceability to internationally recognised national standards. Traceability is vital for all measurement, it gives you confidence that the measurements you make are correct and will be consistent with those made in other places by other people.

Unique identification

For us to provide full traceability to your weights each weight needs to be uniquely identifiable. However labels and tags can interfere with the mass value. Weights are identified by marking with a permanent ink/paint or by stamping. Weights of higher accuracy have specific requirements, in these cases it is advised not to mark the weights and to mark the identity on the cases the weights are stored in.


We also offer a weight adjustment service for those weights that have fallen outside of the permitted tolerances as a result of wear and tear. This can be done on most weights for a small fee (information on current fees can be found at Calibration fee/charges).

Calibration frequency 20kg - 1mg mass comparator

During the period between calibrations, weights can gain or lose weight through wear and tear and damage from the environments they are used and stored in. To maintain our impartiality we cannot recommend the frequency you calibrate your weights. Customers usually determine their calibration period by either calculating a suitable period using data collected from a series of calibrations (drift) or by assigning an annual period in accordance with their own internal procedures.

Requesting Calibration

In order to provide an efficient and effective service we require all calibrations to be booked in at least 14 days in advance.

We will endeavour to complete calibration of your weights and have them ready for collection within 10 working days of being delivered. However, in some instances depending on the quantity and standard of weights, this may take longer.

We will always attempt to provide you with an accurate completion date during the booking in process. 


The booking request form is at:

If you require calibration please submit the form to

In addition, we also have the facilities outside of our UKAS accreditation to test weights up to 1000kg and can provide certificates of test for non-standard weights. If you require this service, please contact us as early as possible to get booked in.


Department for the Economy
Trading Standards Service
176 Newtownbreda Road

Telephone: 0300 123 62 62

For calibration services, email:

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